Conventional surgical procedures for pathologies and/or trauma located deep within the body can cause significant trauma to intervening tissues. Open surgical procedures often require a long incision, extensive muscle stripping, prolonged retraction of tissues, denervation, and devascularization of tissue in order to access a surgical site. Most of these surgeries require several hours of recovery room time and several weeks of post-operative recovery time due to the use of general anesthesia and damage to tissue during the surgical procedure. In some cases, these invasive procedures can lead to permanent scarring and pain.
For example, a common open procedure for disc herniation, laminectomy followed by discectomy, requires stripping or dissection of the major muscles of the back to expose the spine. In an open posterior approach, tissue including spinal nerves and blood vessels around the dural sac, ligaments, and muscle must be retracted to clear a pathway from the skin to the disc. These procedures normally take at least one to two hours to perform under general anesthesia and require post-operative recovery periods of at least several weeks. In addition to the long recovery time, damage to tissue is a major disadvantage of open spinal procedures. As a result, many patients may be reluctant to seek surgery as a solution to pain caused by spinal conditions.
Minimally invasive alternatives, such as endoscopic techniques, reduce pain, post-operative recovery time, and damage to healthy tissue. In minimally invasive surgery, the site of pathology is accessed through portals or a small incision rather than through a significant incision, thus preserving the integrity of intervening tissues. These minimally invasive techniques also often require only local anesthesia. The avoidance of general anesthesia can reduce post-operative recovery time and the risk of complications.
Minimally invasive surgical techniques are particularly desirable for spinal and neurosurgical applications because of the need for access to locations deep within the body and the danger of damage to vital intervening tissues. For example, such minimally invasive techniques can be utilized for spinal discectomy, or removal of an intervertebral disc, and spinal fusion, in which two or more vertebrae are fused together to stop the motion between them. In such minimally invasive, or micro-surgical, procedures, the disc can be accessed by creating a pathway from the surface of the patient's back to the disc through a percutaneous portal or small incision. Such endoscopic surgical techniques typically utilize a tubular structure known as a cannula which is inserted into the percutaneous portal or small incision to a location in the body. The cannula holds the portal or incision open and serves as a conduit extending between the exterior of the body and the local area inside the body where the surgery is to be performed. Small diameter micro-surgical instruments may be passed through the cannula and, for example, into the disc. The intervening tissues are disrupted less because the incision and the exterior-to-interior pathway are smaller.
Although these micro-surgical procedures are less invasive, they can still involve some of the same risk of complications associated with open procedures. For example, the relatively small size of the passage into the body defined by an access cannula adjacent vital anatomical structures can allow injury to those structures, such as the nerve root and dural sac.
Thus, it may be desirable to provide a device capable of protecting anatomical structures along a surgical access pathway in a minimally invasive surgical procedure.